Heat transfer in multi-phase flow
 

I have been trying to simulate a multi-phase heat transfer problem. Purpose is to look for thermal stratification in a concrete reservoir, two-third of the reservoir is full with water, rest is air. I have divided the domain into two regions - solid and liquid, then liquid as a air-water mixer. I have used a field function to define the water air interface. I am running the model in unsteady mode and have not seen any reasonable results so far. Can anyone please help me to define the correct boundary conditions for the model?